[Jrahn56]

My air problems continue to plaque my coach. I've replaced the Governor on the Compressor and relocated the Governor to the right rear compartment forward wall with a new separartion filter, and new air lines, the PPV on at 70 psi, off at 75 psi , Control Valve on my Air Dryer, the Heater Selenoid on the Air Dryer, disassembled and cleaned the Air Dryer. 

The  problem I have now is my drive axle air bags are not inflating and my air is back stuck at 75 psi. The front and tag axle bags inflate. I have the coacch plugged into an external air source as I purchased an ultrasonic leak detector from UE Systems which has helped me locate a few leaks, which I've repaired. I also found 4 ride stabilizers and purchased them as I have a very small leak on the right side, very small bubbles, but a leak. 

I replaced my 12 volt air compressor in 6/24, it comes on maybe once a day for 1 minute 30 seconds, builds 100 psi, enough to flush the toilet but not enough to operate the pocket doors. I rebuilt the original 110 volt Gast compressor with factory rebuild kit as I had a cracked cylinder head, which didn't help. I am in the process of replacing the Gast with a new twin cylinder California Compressor with higher cfm capacity. When I plug in external air I can operate the pocket doors and generator slide, but brake and supply won't get higher than 75 psi. Unplug the external air supply and my supply pressure drops almost immediately, while brake pressure has only dropped 2 lbs. in 3 hrs. 

I am hoping somebody has some directions that will help me solve these ongoing air issues.

Thanks so much,

Jeff Rahn

[Richard]

I know I sound like a broken record. You have a HUGE leak, until you find it, you will make no progress. The obvious question is where? None of us can tell you. You must look everywhere that air is piped or used.

If I were faced with this situation and having difficulty isolating the problem, I would start by adding isolation valves to different systems.

[Jrahn56]

I know I sound like a broken record. You have a HUGE leak, until you find it, you will make no progress. The obvious question is where? None of us can tell you. You must look everywhere that air is piped or used.

If I were faced with this situation and having difficulty isolating the problem, I would start by adding isolation valves to different systems.

Thank you Richard, I've ordered some inline 1/4 turn shut off valves to do that. Not sure why the front and tag bags inflate and the drive bags don't. I have my coach up on 4 30 Ton Jack Stands for safety. I was under the coach today with the ultrasonic leak tester and found 2 leaks and replaced the air lines in both cases, but I didn't hear anything around the drive bags on either side. This coach is driving me crazy. I was told by a member to replace the PPV and I needed one that was on at 70 psi and off at 75 psi, is that correct? Because I am only building 75 psi, does the PPV control that even when the motor is not running and I am airing up with an external air source?

Thanks again,

Jeff

[johnkosir]

I agree with Richard the reason I have shut off valves on every line coming off my tanks is because I have a small leak I can not find. I would do it a little different when I had the line off to put in the shut off valve I would put my bubbler in series with the tank and I could see how much air is going down that line. you could also just use a gauge put air pressure in the line, turn off the valve which is between the compressor and the gauge  and watch the gauge where your big leak is the air pressure will drop real fast, I would also figure out where the line goes and mark it. then do the next one.

[Jrahn56]

John, if I understand you correctly, I find the line coming off my compressor to the tank (that would be the round brake supply tank and the tank in the cross member) near the Drive and Tag axles? What about the front tanks. When I went to bleed off the front tanks (2 round and 1 cross member) I bled the 2 round tanks and no moisture, but very little air pressure. The cross member tank I could not get the drain plug loose. Soaked it with penetrating oil, will check in a day or 2.

Thank you for your help.

Jeff

[johnkosir]

No I did not explain it properly. I would use a external air compressor to supply the air lines leaving your tanks to see which one has the big air leak, your coach is a lot older than mine and I am not familiar with how yours is plumed.

[HoosierDaddy]

Jeff. What part of the country do you live? What is your coach number?

[Jrahn56]

I am from Tucson, but currently on a project in El Paso, TX. Currently residing at Mission RV, where the coach is up on 4 30 ton jackstands so I can get under it safely, that is.when my asthma doesn't have me sidelined, like yesterday. I appreciate any suggestions you might have. A comprehensive owner's manual showing how these coaches were plumbed and what were used would come in awfully handy right about now. Something Newell should consider doing, like Prevost and MCI do. Wishful thinking.

Thanks again for your support.

Jeff Rahn

[Richard]

Jeff,

In specific regard to tag and front bags filling but drives not filling. Do you have one or two six packs in the rear engine compartment. The approach and solution is very dependent on which setup you have.

And my thinking, perhaps incorrect, is that your problem has nothing to do with the PPV. Yes you are topping out at 75 psi, but as soon as you disconnect air, you drop to zero in a very short time. My idea is the leak is SO big that no amount of input air can make up for the leak. Could be wrong, often I am.

And one more thing that doesn’t compute to me about your comments. You said the 12V compressor will build 100 psi, enough to flush the potty, but not enough to open the pocket door. On that era coach I am not sure IF the pocket door was plumbed into the 12V or not. No two Newells are the same, and who knows what air system plumbing changes were made over the years.

[Keith Jordan]

12v compressor on 390 operates the toilet and nothing else